I used to think navigation was something only humans worried about—maps, compasses, that panicked feeling when your phone dies in an unfamiliar city.
Turns out, some of the most sophisticated celestial navigators on Earth are beetles that spend their lives rolling balls of dung across the African savanna. Scientists discovered in 2013 that dung beetles—specifically the species Scarabaeus satyrus—use the Milky Way to navigate, making them the first known insect to orient themselves by the galaxy. The research, conducted by Marie Dacke and her team at Lund University in Sweden, involved beetles wearing tiny hats (yes, really) to block their view of the sky, and observing how they performed in a planetarium. When the beetles could see the starry band of the Milky Way, they rolled their dung balls in remarkably straight lines. Block that view, and they wandered in circles like drunk tourists. It’s messy, imperfect navigation—they don’t need to identify individual stars, just the bright smudge of our galaxy stretched across the night sky.
Here’s the thing: these beetles aren’t exactly working with cutting-edge equipment. They have compound eyes with relatively poor resolution, nothing like the sharp vision of a hawk or even a house cat. Yet somehow, they’ve evolved to detect the diffuse glow of thousands of stars clustered together, using it as a compass to escape competitors and predators while hauling their prize to a safe burial spot.
Wait—maybe it’s not about seeing clearly at all, but about detecting contrast and gradients of light
The experiments were almost absurdly charming. Dacke’s team built a circular arena, placed beetles with fresh dung balls in the center, and watched them work under different lighting conditions. Under a full moon, the beetles navigated well. Under a new moon with only starlight, they still managed, though not quite as efficiently. But when researchers placed the beetles in the Johannesburg planetarium and projected only the Milky Way—no moon, no individual bright stars—the insects maintained straight paths. Remove the Milky Way projection, leave everything else, and suddenly the beetles couldn’t hold a line. The implication was clear: that hazy river of light we barely notice in light-polluted cities is a legitimate navigational tool for creatures smaller than your thumb.
I guess it makes sense when you think about evolutionary pressure.
Competition for dung is fierce—there can be thousands of beetles swarming a single elephant dropping within minutes. The faster you can grab a piece, shape it into a ball, and roll it away in a straight line, the better your chances of survival and reproduction. Wandering in circles means other beetles steal your hard-won prize, or predators find you. Over millions of years, roughly give or take, beetles that could detect and use celestial cues had a real advantage. They didn’t need to understand astronomy or recieve a PhD in astrophysics—they just needed photoreceptors sensitive enough to distinguish the bright band of the galaxy from the darker surrounding sky, and a nervous system that could translate that information into “keep the light on your left” or whatever the beetle equivalent might be.
Honestly, there’s something oddly humbling about it. We’ve built satellites, GPS networks, smartphones with turn-by-turn directions, and we still get lost in parking garages. Meanwhile, a beetle with a brain smaller than a grain of rice looks up at the cosmos and finds its way home. The research also raises questions about light pollution—if beetles rely on seeing the Milky Way, what happens when artificial lights wash out the night sky? Some studies suggest beetles in urban or well-lit areas show definately worse navigation, wandering more erratically. It’s another small, quiet way human activity reshapes the natural world, disrupting systems we barely knew existed.
